Catalyst regeneration



J. W. BARKER CATALYST REGENERATION July 24, 1951 Filed 001. 15, 1948 JomZZHr/fef Gitorneg 6 L M 5 l. 7 NM J M m M M w M. E w m 6 MMG W R M M WNMG M W MS m W M a c a M f c F MK? a 6 we m z a; 2 c c m m n f f f T 7 i@m .f a/ 1 5.7 i z ,zh ,um n. l a M r M N 1 mm M w\ 7- 1 Hwwl ,-11 Alah.. ,.f .i1 ifi?. J Z w 1 Z fr. 1111 n m wma M w m@ Patented July 24,1951 UNITED STATES PATENT OFFICE CATALYST REGENERATION ApplicationOctober 15, 1948, Serial No. 54,621

3 Claims. (Cl. 252-418) The presentinvention is directed to improvementsin methods and systems for reactivation and regeneration of solidcontact masses containing combustible deposit therein. It isparticularly concerned with the construction and operation ofregeneration kilns of the type wherein a moving body of contact masscontaining carbonaceous deposit, such as used catalyst from ahydrocarbon conversion step, is brought into contact with an oxidizingor combustion-supporting gas to efIect burning of such deposit.

Processes for catalytic cracking of hydrocarbon oils are well known andin extensive commercial use. In typical processes, a hydrocarbonfraction, such as a gas oil, is brought into contact in vapor form andat temperatures of about 800 F. or above with a particle form solidcontact mass having catalytic activity, thereby effecting conversion ofa substantial part of the hydrocarbons to gasoline. In common use ascatalysts for the purpose are natural and synthetic siliceous adsorptivemasses, such as chiefly acid-activated clays and dried gels comprisingsilica and alumina. Similar systems and arrangements are often used inthe treatment of gasoline and naphtha fractions to obtain improvementsin the quality thereof such as upgrading cf the octane rating; thesetreatments are commonly referred to as catalytic treating or reforming AWidely used system for carrying out such reactions involves anarrangement wherein the particle form solid contact mass is movedcyclioally through two separate vessels in the first of which thedesired hydrocarbon conversion reactions are carried out, and in theother vessel the used contact mass from such reactions is regenerated bycontact with air or other oxygencontaining gas effecting burning of thecombustible deposit called coke formed in such mass during thehydrocarbon conversion reactions. The regenerated contact mass is thenreturned to the rst vessel for further use therein.

The regeneration of a catalytic contact mass by burning of thecombustible carbonaceous and/or hydrocarbonaceous deposit thereininvolves exothermic reactions which raise the temperature of the mass.The minimum temperature at which initial combustion of the deposit willtake place is at about 750-800 F. and with continued burning the amountoi heat liberated causes increase in the temperature of the mass suchthat, unless suitable controls are provided, temperatures are reachedwhich may result in permanent injury to the mass. For instance, it hasbeen observed that active clay `cracking catalysts may be impaired whenregeneration temperatures are permitted to exceed about 1150 F. or so,for any appreciable length of time in the presence of quantities ofsteam adsorbed in the catalyst prior to regeneration as well as thatreleased from burning of the hydrocarbonaceous deposit thereon;synthetic catalysts ordinarily can withstand higher temperatures. To`avoid excessive and injurious temperatures provision is made for removalof heat from the regeneration kiln. In typical commercial installationssuch heat removal is brought about by the provision of vertically spacedcooling sections in the form of coils circulating a heat transfer mediumfor indirect heat exchange at different selected levels in the kiln.

The present invention has among its objects to provide a simplied kilnconstruction and operation wherein eflicient regeneration of catalyst isobtained with important savings in operation and maintenance costs, inaddition to notable economies in equipment construction costs.

In accordance with the present invention, regeneration of catalystcontaining coke from a previous hydrocarbon conversion operation iseffected by passing the contaminated catalyst, as a compact downwardlymoving bed, through a kiln providing several contiguous zones in which 1the catalyst is subjected to contact with countercurrently flowingregenerating gas, such as air or other oxygen-containing gas, to effectcombustion of the coke. The regenerating gas is separately admitted atthe bottom of each of such zones and the iiue gas resulting fromcombustion of the coke is separately discharged atv the top of eachzone. Admission of gases from one re-` generating zone to the other isinhibited by maintainingtthe outlet pressure of the flue gas from onezone substantially equal to the inlet pressure of the regenerating gasin the zone directly above.

By operating the kiln in the above described manner the pressure dropsof the gases passing upwardly through the several zones in the kiln arerendered additive. The total pressure drop of the gases ovving throughthe kiln thus can be advantageously utilized in accordance with theinvention to help balance the pressures employed :in the remainder ofthe system and thereby reduce the seal leg requirements in the system.In hydrocarbon conversion systems wherein the reactor and kiln arelocated one above the other, such reduction of seal leg requirements isparticularly important from the standpoint of decreasing the over-allheight of the system.

The entire regeneration is carried out asa stage operation but undercontrolled conditions such that only counter-current iiow between theregenerating gas and the descending catalyst is utilized in each stage.By this arrangement there is obtained as one important advantage a lowconcentration of oxygen in the vicinity of high coke content on thecatalyst and a maximum oxygen concentration in the vicinity of thelowest coke content, thereby permitting unhindered burning of coke underconditions prevailing in the several zones of the kiln without causingoverheating of the catalyst. Thus also, the gas of highest oxygenconcentration is initially brought into contact with partiallyregenerated catalyst containing the last' vestiges of coke', Which cokeis the most diflicult to burn, and under conditions of high pressurefavoringburning of such coke. Partially spent regenerating gas isprovided in the appropriate zone and is utilized in the initialcombustion stages, before the regeneration has progressed to maximumoperating temperature, to contact catalyst having its full'complement ofcoke. Accordingly the control'ofltemperature along'the length of thekiln tends to be self regulating to meet the diiTerent c" requirementsWhile the development of excessive temperatures is inhibited.v

1n accordance with a preferred embodiment, the regenerating gasintroduced directly into the several zonesof the kiln is cool air;conveniently atsubstantial'ly the temperature reached by coinpression ofatmospheric air, which cool air serves einciently to remove sensibleheatfrom the cata- Iy'st by direct thermal exchange, thereby provid'- ingfurther safeguardsA against detrimental temperatures while operatingclose to maximum desired temperature and further reducing theoveral-lcooling coil requirements. The space which would otherwise berequired for additional cooling'equipment can be thusutilized to provideincreased-"useful volumetric capacity of the kiln, if desired, or theoverall size can be reduced for any given coke-burning capacity.

Other advantages ofthe improved kiln design and operation of theinvention will be apparent from the description which follows read incon- I'iection with the accompanyingk drawings illustrating one form ofapparatus-adapted to practice of' the invention.

In' the drawings, Figure 1 is a largely diagrammatic vertical elevation(portions being broken away and shpwn in cross-section) of one formassembled unit embodying the novel kiln de'- si'gn; Figures 2 to 5 arehorizontal cross-section viewstaken respectively on lines 2 2, 3 3, 4-4and 5--5of' Figure 1; Figure 6 is an enlarged view in" perspective,illustrating the relation between a gas'supplymanifold and connectingdistributing channels; Figure '7 is a similar View of a gasdischargemanifold and collecting channels; Figure Sis a partial verticalcross-section illustrating a modied gas. discharge arrangement.

Referring now more particularly to Figure 1, there is lshown an assemblyin superimposed relationiof a catalyst supply hopper i a hydrocarbonconversion reactor 2 and a kiln 3, with inter-connecting conduits 4 and5 through which the catallyst is passed respectively from the hopper tothe reactor and from the reactor to the kiln. Catalystis admitted to thehopper Il by means of conduit 6 and discharged from the bottom of thekiln by means of the conduit 1. vThe regenerated catalyst dischargedfrom the bottom of the kiln through the conduit 'I is returned bysuitable means to the conduit 6 for supply to the hopper discharge linewithv the duct II'.

l. Such means may comprise the well known bucket type of mechanicalelevator (not shown), for instance the type illustrated in the Simpsonet al. Patent U. S, 2,336,041 of December '7, 1943. instead of amechanical elevator, a pneumatic type lift may be substituted forelevation of the catalyst.

In the catalyst supply hopper I, provision may be made for the admissionof steam into contact with the catalyst, as by means of a supply line 8and louvered distributing member 9. The distributing member 9 as shownis located in a portion of the hopper which is of reduced crossseetion,being adjacent the downwardly converging Wall lil of the hopper, and asresult thereof eicient distribution of the steam into contact with allportions of the catalyst is obtained.

Within the reactor 2, the catalyst is contacted with hydocarbons to bereacted and the gaseous reaction products are discharged from thereact-er, The hydrocarbons may be charged to the reactor so as to flowconcurrently With the descending catalyst or counter-currently thereto.In a concurrent operation, for instance, the hydrocarbons are admittedthrough a supply line connecting with the duct II and the gaseouseiliuent, discharged through a line connecting with the duct l 2. In thereverse operation, the supply Line will be connected. with the duct I2and the Suitable provision is made in either casxfory disengaging ofvapors from the catalyst'.

, Communicating with the interior of the lower portion of the reactor 2and below the level.v of

.f the duct l2, a line I3A is provided for the admission of purge gas,such as steam, to free the catalyst being discharged from the reactorfrom condensed liquid o il and polymer. Ii the reactor iseperatedconcurrently the purge gas admitted through line I3 is dischargedtogether with hydrocarbon conversion products through the duct i2. Inthe reverse operation, if desired, all or part of the purge gas may bepermitted to pass upwardly. through the descending catalyst bed for,discharge through the duct I I with the formed hydrocarbon conversionproducts.

At the top of the kiln 3, means are provided for the admission of sealgas, as through line Id. In the preferred operation a portion of theseal gas will be permitted to flow upwardly through the conduit 5,vtheremainder iiowing downwardly beingdischarged with flue gases throughthe duct I5. Admissionof seal gas through line I4 is controlledjby valveIt, operated automatically by a differential pressure control means I1,which is set to maintain the desired differential pressure between thebottom of the reactor and the top ofV the kiln. Undesired and dangerousadmixture of gaseous products between the reactor andkiln is thusprevented.

The design and operation of the kiln proper will now be described, Thecatalyst admitted through the conduit is discharged into the kiln onto atube sheet I8, having distributing downcomers I9 suitably arrangedtherebelow to distribute the catalyst uniformly over the entirecross-section of the kiln. Below the discharge outlets of the downcomersI9, cooling coils 20 are provided through which a heat exchange fluid iscirculated in known manner. The extent of cooling surface to beprovided, of course, will depend upon the temperatures designed to bemaintained and' the thermalv balances involved in the operation..Regeneratinggas is admitted to the kiln atleast at several levels; twoof which are shown. Thus, regenerating gas may be ad'- mitted at anintermediate level of the kiln through the duct 2| and at a lower levelof the kiln through the duct 22, these ducts being connected to suitablesupply lines. The ducts 2| and 22 may be interconnected by a manifoldprovided with proportioning devices or separate supply lines may beused, particularly if regenerating gas at different temperatures is tobe employed at the several gas inlets. Discharge of flue gases formedduring regeneration in the zone above the inlet duct 2| is had by meansof the duct I5 communicating with a plenum space provided above thelevel of the catalyst bed, wherein separation of gas from the catalystis easily effected. The duct I5 is in turn connected to a flue gasdischarge line (not shown).

The distribution of the incoming regenerating gases admitted throughducts 2l and 22 is effected similarly in both instances. As shown, theduct 2| communicates with a distributing manifold 23, which manifold inturn communicates` with a series of open bottomed channel members 24,distributing the admitted gas uniformly over the entire cross-sectionalarea of the kiln. The duct 22 in similar manner is connected to adistributing manifold 25 and communicating channel members 26. Detailsof the construction of the gas distributing manifolds and associatedchannel members are more fully shown in Figures 4 and 6.

The gas admitted through duct 22 and distributing manifold 25 passesupwardly through the kiln and is discharged below the level of manifold23, by means of a duct 21 and communicating flue gas discharge line. Theformed flue gas is collected by open bottomed channel members 28,communicating with the discharge manifold 29, which in turn is connectedto the duct 21. (See particularly Figure 7.) To maintain separatecontrol of the upper and lower regenerating zones, admission of flue gasfrom the regeneration Zone below to a succeeding zone above issubstantially prevented. This is accomplished by maintainingsubstantially zero pressure drop between the inlet duct 2| and thedischarge duct 21, by suitable automatic differential-pressureresponsive flow control means. In the present instance, there is shown adifferential pressure controller 3!! with appropriate connections, whicharrangement can be set for a Zero pressure drop across the pointsindicated; or if desired, the pressure at inlet duct 2| may be slightlyabove that at discharge duct 21.

Intermediate the inlet duct 22 and the bottom discharge outlet duct 21,additional cooling means are shown at 3|. One or more banks of suchcooling coils may be provided in this lower portion of the kiln asrequired by the conditions of the operation.

To secure uniformity of catalyst flow in the kiln, the discharge ofcatalyst across the area of the kiln is equalized by a tube sheet 32 anda series of perforated distributing plates such as 33, 34 and 35, thebottom of the kiln being made conical as indicated at 35, converginginto the conduit 1. The tube sheet 32 is provided with downcomers 31uniformly spaced over the area thereof and providing an ample plenumspace below the tube sheet. For certain operations it may be desirableto admit gas for pressureV or purge into the lower portion of the kiln.Accordingly, a valve controlled gas inlet is provided at 39communicating with the plenum space formed below the tube sheet 32.

In Figure 6, a modified arrangement for separation of flue gas fromcatalystis shown, which may be substituted for the channel members 28and' manifold 29. Thus, a tube sheet 40 may be used, provided withuniformly spaced downcomers 4I, providing a. plenum space as indicatedat 42, communicating with the discharge duct 21 and operating in similarmanner to the space above the catalyst bed communicating with the ductI5.

l It will be understood that in practical oper-v ation of a system ofthe type described, automatic control means will be provided to regulateand maintain desired pressures, and control flow of catalyst and gasesin various parts of the system. These control means being generally wellunderstood in the art, for the purpose of simplicity, theinstrumentation is not shown in the drawings except in a few instances.The valve controlled line 45 at the top of the hopper I serves tomaintain a set pressure in the hopper while removing any seal gas andunadsorbed steam above the catalyst bed in the hopper. Avalve-controlled line 45 is also provided at the top of the reactor,which can be used, depending upon conditions of operation, for admissionof seal gas such as steam or inert gas, or in other types of operationfor discharge of gases, such as a portion of the steam which may bepermitted to 'enter the top of the reactor through conduit 4.

The type of arrangement illustrated in Figure l, is a designparticularly adapted to be Shop pre-fabricated for small capacityinstallations, such as those circulating up to about 350 tons ofcatalyst per hour. aged unit, when constructed of suitable diameter (asup to about l2 feet) and in sections of appropriate lengths (as up to nomore than about 60 to 70 feet per section), the individual fabricatedsections can be shipped to an erection site in railway flat cars.Assembling of the unit then requires only simple operations at the site,such as joining of the sections and attachment of conveyors and piping,with consequent savings in construction costs. For added rigidity ofconstruction, reinforcing shells may be provided, as shown at 41 and 48(Figure l) between the several sections ofthe unit.

The described kiln of the invention and its operation are not limited touse with arrangements of systems as shown in Figure 1; the same type ofimproved kiln may be employed in other arrangements, such as in systemswherein the kiln is located above the reactor, or the kiln and reactorare located side by side.

The improved kiln design provides wide flexibility of operation from thestandpoints of desired pressure balance and thermal balance. In allinstances, however, because of the pressure drops through the kiln beingadditive, the total pressure drop obtained in the kiln can be employedto reduce the seal pressure requirements of the system. In this manner,for instance, the pressure drop through the kiln can be used to breakdown the existing pressure at the top of the reactor supply hopperand/or at the topv of the reactor. If the system is arranged with thereactor and kiln in superimposed relation, the described kiln can beoperated under conditions to maintaina comparatively high pressure atthe discharge of the lowermost vessel (be it reactor or kiln), whichhigh pressure has. particular advantages for use in combination with apneumatic lift type of elevator. On the other hand, high pressure at thedischarge outlet of the bottom vessel is not ordinarily desired with amechanical elevator, and accordingly` in this com- With this form ofpack T, bination. it. may be; more desirable :to operate the systemwith:the lowest pressure that' can be ex pediently hadat thedischarge: outletofY the bottom vessel. Advantageously, with. the arrangementshoWnfinFigurefl, if operated withfa` bucket.

type-elevator, it isY preferred to enclose the. ele-- vator. in apressuresealed housing, so that. the. pressure existing at the outlet ofthe kiln can be substan-tially maintained at the dischargeof theelevator to the inlet of the suppl-y hopper I.

The following is an example of distribution of gas pressuresinpracti'cali operation of anv arrangement as illustrated in Figure 1,wherein. advantage is taken or the pressure drop-in. the.. kiln torreduce the total. seal leg requirements theconduits 4, 5, 6 and 1. Thepressure at. the bottom of the'elevator and'y the'top of the reactorsupply hopper. I may be set at about. 6 pounds per square inch: gauge,which pressure can`- be. maintained during transportation of the.catalyst in the elevator by admission of an inert. gasinto the' elevatorhousing; Introduction of steam through line 8 need be` at only aslightly higher pressureto overcome the slight drop through. the hopper.In a concurrent operation. the hydrocarbon charge may be" introducedthrough duct I.I at sayr 8 pounds per square inch gauge, and thevaporous conversion products dischargedthrough duct 12 at say 6 pounds.The conduit 4, to operate as a seal leg would therefore have to be ofsuflifcient length'. to provide a pressure drop of. about 2 pounds. Theseal is maintained by. introducing a seal gas, whichmay be steam,through line 46, at a pressure slightly above 6 pounds.. A

portion of the seal gas will dow up the leg 4, Y

the remainder being permitted to enter the re actor.

Steam or inert gas mayl be admitted through line I3 for purging thespent catalyst atslightly above the 6 pound pressure-at discharge ductrI2., say at- GA pounds; a portion of the steam or inert. gas will bedischarged with the hydrocarbons through the duct I2.

The kiln may be operated under conditions such that the total pressuredrop through the. kilnY is about 2 pounds. This drop is had, forinstance, by admitting regenerating gas through d-uct 22 at 4 pounds,withdrawing ue gas through duct 2l at say 3 pounds, admittingregeneratinggas through duct 2| at the same 3 pounds'andy withdrawing uegas through duct I 5 at2'pounds. The 4 pound diierential pressurebetween the level of line I3 and the top flue gas'outlet f5, will thenbe taken up in the sealrleg provided by conduit 5. The diierence inpressure between the foot of the elevator and the discharge outlet ofthe kiln can be made. up by admissionl of pres.- suring gas into theconduit 1, for instance by admission of iiue gas, steam or inert gasthrough duct 39. It will be understood that to maintain the requiredpressure seal, conduit 'IV may be pro-Y vided with suitable controls,such as a chopper valve, approximate its outlet to the elevator.

In an alternative arrangement with the' kiln located above the reactorthe advantages of the present kiln design from the standpoint of reducedoverall seal leg requirements will in most instances be even morepronounced.

In certain arrangements, such as Where the kiln is supplied withcatalyst directly from' an elevator, it is preferred to discharge the uegas from the top of the kiln at about atmospheric pressure. In this way,the elevator bringing catalyst to the top of the kiln need not besealed' against the outside atmosphere.

The following example istypical of' a catalytic ing over thetop coolingsection 2.0.

Y standard cubic feet of air a minute admitted.y

through ducts 2| and22. The air may bel ad'- mitted. at compressiontemperature of say about. 100 Flue; gas may be discharged through the;duct. I5 at atmospheric pressure or any desired i pressure. thereabove,taking into account. the' pressure existing at the discharge of thereactor 2.

Catalyst may be admitted tov the kiln atsay 925 F. and'will be cooledsome 15 to 25., in.pass,-

On descent: of the catalyst through the kiln and contact withl the airor other regenerating gas admitted through duct 2|, the temperature oftheA catalyst is progressively increased and will reach asY a result ofcoke combustion about 1050 to 1075*" F.,.above. the level of themanifold 23 and its con-- necting channels. In contacting fresh coolerail: in that vicinity, the catalyst will be cooled. downbyl efficientdirect heat exchange therewith to about' 1025"' F. Descending furtherbelow the flue. gas manifold 2.9, the catalyst will` again beraised intemperature by combustion of coke in the, presence of the' air admittedthrough duct 22, and willV reach a maximum regeneration tempera-- turedirectly above the lower cooling coils 2'I, ofi about 1150 F. In passingover the cooling coils 2'I catalyst will be cooled some 25-50", andbeflow the cooling coil will again be raised inv tem.- perature ultimatelybeing cooledv by direct contact with the cold air entering through duct22' to approximately its desired discharge temperafture of about 1100 or1110D F. The extent of cool-y ing by the coilsv 21 may be adjusted togive the desired catalystV discharge temperature. The

fz: pressure drop of the air in passing through the and the dropdistributed along the several zones of' the kiln. Thus, the ue gas canbe withdrawn through duct 26 atA 11/2 pounds gauge and to maintain azero pressure drop between the flue gas outlet 26 and the upper airinlet 2l, the regenerating gas will be admitted through duct 2| atsubstantially the same pressure, 11/2V pounds gauge. The pressure dropthrough the bed above the manifold 23 and cooling coils 20 can then beabout 11/2' pounds to bring the top of the kiln to atmospheric pressure.

The described kiln operation obtains additional important advantagesWhen the coke content of the catalyst as discharged from the reactor iskept low. This condition obtains, for instance, in carrying out thehydrocarbon conversion operation using high ratios of catalyst to oilcharged. For example, in charging of a given heavy gas oil to acatalytic cracking operation at a fixed space rate and selectedoperating variables such as temperature and pressure, a certain quantityof coke Will be produced in the operation per unit time. By keeping theother factors of the operations constant but increasing the mass rate atwhich catalyst is passed through the reactor, that quantity of coke willbe distributed over a greater quantity of catalyst and the percent ofcoke per unit weight of. catalyst is thereby decreased. With usualcharge stocks, cracking conditicms giving desirable distribution .ofcracked products can be maintained at catalyst-'to-oil vratios in excessof five and up to ten or more .with consequent deposition of less than1% by weight of coke on the catalyst, say approximately 0.4 to 0.8 byweight. In the regeneration of the oatalystof lthis low coke content,employing the described improved kiln operation, it will be seen, lesscooling ofthe catalyst during the course of regeneration is required tokeep within safe maximum temperatures.' Also, in maintaining the desiredthermal balance, a lesser quantity of heat needs to be removed toprovide regenerated catalyst at desired temperature for reuse in thereactor. The novel kiln design and operation of the invention is exiblyadapted for beneficial use with the described hydrocarbon conversionoperationsv wherein catalyst of low coke content is presented forregeneration.

In adapting the operation ofthe kiln to particular hydrocarbonconversion operations, the ultimate discharge temperature of thecatalyst and the degree of cooling of the catalyst in a kiln of ixeddimension and design may be controlled over a wide range by thetemperature and/or rate of admission of the regenerating gas, by thetemperature at which the indirect heat exchange fluid circulated throughthe cooling coils is maintained, which may permit blanking out one ormore of the cooling coils provided. For instance, with less coke to beburned per weight of catalyst, the upper cooling coil may in someinstances be disconnected; or, if desired, regenerating gas at highertemperature as up to prevailing regenerating temperature may be admittedthrough the inlet 2l. In the lower section of the kiln, likewise theflexibility of the operation is extended by similar controls provided inthe selection of regenerating gas temperature and indirect coolingsurface provided by the coil 2l.

rIhe following example is typical of a complete cracking andregenerating operation employing a system of the type illustrated inFigure 1. Acidactivated clay catalyst is employed for cracking of areduced East Texas crude oil of about 25 API gravity at an averagetemperature of about 900 F., employing a catalyst-to-oil weight ratio of5 and a volumetric space rate (measured as liquid) of 5, giving about.7% to 1.0% by weight of coke deposited on the catalyst. In a systemcirculating 500 tons of catalyst per hour, and some 7000 pounds of cokeare to be burned during regeneration, approximately some 25,000 standardcubic feet of air per minute will be employed.

If the catalyst is brought into the reactor at about l050 F. and the oilcharged at say '700 F., (employing concurrent flow) the catalystdischarge temperature may be at about 900 F. By admitting air asregenerating gas at about 100 F. (the temperature of compression ofatmospheric air) and appropriately distributing the air between theseveral inlets, the maximum temperature of combustion will be reachedjust above the lower cooling coils 21, at say about 1150 F. The catalystis ultimately discharged from the kiln at about 1000 F. and is broughtto reactor inlet temperature of 1050 F. by hydration with steam.

The regenerating gas admitted through the several inlets to the kiln,such as ducts 2| and 22, may be supplied from a common manifoldcommunicating with a blower or gas compressor, reduction valves beingemployed to obtain the desired different pressures at the several gasinlets. The described arrangement, however, permitsl the use of separateblowers or compressors connected with each gas inlet, thereby affording-further economiesjin'operation by taking advan- -tage of the lowerpressure requirements at the intermediate inlet levels.

y Obviously many modilications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof and therefore only such limitations should .be imposed asare indicated in the appended claims.

I claim as my invention:

l. The process of regenerating catalyst containing =carbonaceous depositresulting from use of the catalyst in a hydrocarbon conversionoperation, which process comprises burning of said carbonaceous depositin a plurality of separately controllable combustion stages, wherein thecatalyst. during regeneration is passed through each of said stages as acompact downwardly moving bed 4and ,wholly in counter-current contactwith upwardlyA owing oxygen-containing regenerating gas separatelyintroduced under pressure in each of saidcombustion stages, dischargingthe gaseous products o combustion thereby formed in each combustionstage separately and substantially entirely from that stage and at apressure substantially equalvto the inlet pressure of the regeneratinggas introduced into a preceding combustion'g stage immediatelythereabove, thereby avoiding direct admissionof material quantities ofcombustion products formed in one of said combustion stages to anotherof said stages, the downwardly moving bed of catalyst in passing throughsuccessive combustion stages being subjected to increased gas pressurein each succeeding combustion stage.

2. The process of regenerating catalyst containing carbonaceous depositby contact with oxygen-containing gas, which comprises passing thecatalyst in hot state downwardly as a compact bed through a plurality ofcombustion zones, contacting the catalyst in each of said zones withcounter-currently flowing oxygen-containing gas separately introducedinto each of said zones from an external source, withdrawing formedgaseous combustion products separately from each of said combustionzones, and so controlling the gas pressures at the regions ofintroduction and withdrawal of said respective gases into and from saidcatalyst bed that downward flow of gases through said catalyst bed isopposed, whereby the pressure drops due to the flow of said gasesthrough the catalyst bed are additive in a single direction, saidcompact bed of catalyst in passing downwardly through said plurality ofycombustion zones being subjected to successively increased gaspressures.

3. The method of catalyst regeneration which comprises continuouslypassing hot coke-containing catalyst from a catalytic hydrocarbonconversion operation downwardly to an enclosed regenerating region,reducing the temperature of catalyst entering the regenerating region inan initial cooling zone by indirect heat exchange. thereaftercontinuously passing the catalyst so reduced in temperature downwardlyas a compact bed through uninterrupted treating zones hereinafterrecited: rst, through an upper combustion zone wherein the catalyst iscontacted with oppositely flowing oxygen-containing gas to effectcombustion of a portion of the coke content of the catalyst therebyincreasing the temperature of said catalyst to above the temperature ofSaid catalyst prior to said initial cooling but below desired maximumtemperature of regeneration; then, through a direct heat exchange zonewhere erated catalyst as a compact bed from said upperrfco'1iiloustir'nfi 'Z'on'e to alower combustion zone, contaefting the'partly regenerated catalyst in said lower ooinblstion tone withobpositely iowing Iregnerating'g'as te 'effect further combustion ofcoke in 'said `catalyst thereby raising the temperature 'oi the catalystto desired maximum temperature, again reducing the catalyst temperatureb'y passing the co'mpaot bed lof catalyst through a ycooling area,Ac'zontacting 'the :thus cooled catalyst a lower -gas inlet zone withfresh regenerating gas directly introduced 'into said zone at a pressure4h-i-'gl'iei' vthan that of the oxygen-Containing Jgas faslintroduc'e'cl into said -Ziir'ect heat exchange zne, and dischargingthe 'regenerated catalyst; the gases from said lower lcombustion zonebeing' sparatcd from the-oatalyst Sand discharged from the 'enel'osedregenerating region 'above said last named fcoolifng area and below saiddirect heat 'ex- 'change "zone, `andfs'aid gases `being discharged 'fromAsaid lower combust'iorilzone at a pressure Substantially equal to theinlet pressure of the oxygencontaining gas introduced into said directheat exchange zone, whereby the direct admission of material quantitiesof gases from said lower combustion Zone to said upper combustion zoneis avoided.

JOHN W. BARKER.

REFERENCES GITE!) The following references `are of lrecord in the le ofthis patent:

UNITED STATES PA'IENTS Number .Name Date 1,784,536 Pantenburg ---nn Dec.9, ,1930 2,311,564 Munday Feb. 16, 1943 2,372,018 Ruthruff 1- 1 Mar...20, 1945 2,409,596 Simpson et al. -h Oct. 15, 1946 2,416,214 Payne aFeb. 18, 1947 12,418,673 Sinclair et al. f Apr. 8, 1947 2,419,517Eastwood 1 Apr. 22., 1947 2,420,904 Noll 1. May 20, 19491 2,423,813Lechth'aer et al. July 8, v1947 2,429,545 Bergstrom Oct. 21, 1947,2,436,780 :Simpson Feb..27, 1948 2,438,261 Utterback Mar. 23, 19482,441,170 Rose :et-a1. ---s w.-- May 11, 194s 2,499,304 Evans Feb. 28,1950

1. THE PROCESS OF REGENERATING CATALYST CONTAINING CARBONACEOUS DEPOSITRESULTING FROM USE OF THE CATALYST IN HYDROCARBON CONVERSION OPERATION,WHICH PROCESS COMPRISES BURNING OF SAID CARBONACEOUS DEPOSIT IN APLURALITY OF SEPARATELY CONTROLLABLE COMBUSTION STAGES, WHEREIN THECATALYST DURING REGENERATION IS PASSED THROUGH EACH OF SAID STAGES AS ACOMPACT DOWNWARDLY MOVING BED AND WHOLLY IN COUNTER-CURRENT CONTACT WITHUPWARDLY FLOWING OXYGEN-CONTAINING REGENERATING GAS SEPARATELYINTRODUCED UNDER PRESSURE IN EACH OF SAID COMBUSTION STAGES DISCHARGINGTHE GASEOUS PRODUCTS OF COMBUSTION THEREBY FORMED IN EACH COMBUSTIONSTAGE SEPARATELY AND SUBSTANTIALLY ENTIRELY FROM THAT STAGE AND AT APRESSURE SUBSTANTIALLY EQUAL TO THE INLET PRESSURE OF THE REGENERATINGGAS INTRODUCED INTO A PRECEDING COMBUSTION STAGE IMMEDIATELY THEREABOVE,THEREBY AVOIDING DIRECT ADMISSION OF MATERIAL QUANTITIES OF COMBUSTIONPRODUCTS FORMED IN ONE OF SAID COMBUSTION STAGES TO ANOTHER OF SAIDSTAGES, THE DOWNWARDLY MOVING BED OF CATALYST IN PASSING THROUGHSUCCESSIVE COMBUSTION STAGES BEING SUBJECTED TO INCREASED GAS PRESSUREIN EACH SUCCEEDING COMBUSTION STAGE.